1Swain, M. Communication competence: Some roles of comprehensible input and comprehensible output in its development [M].Newbury House 1985, 235~253.
2Neman, B. S. 1995 Teaching Students to Write, New York: Oxford University Press, Inc. Silva, T. 1990Second language composition instruction:Developments, issues, and directions in ESL.
3Halliday, M. A. K. An Introduction to Functional Grammar. USA:Edward Arnold USA, 1985.